CN109799302A - The nearly online test method of medium volatile organic compound - Google Patents
The nearly online test method of medium volatile organic compound Download PDFInfo
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- CN109799302A CN109799302A CN201910212822.9A CN201910212822A CN109799302A CN 109799302 A CN109799302 A CN 109799302A CN 201910212822 A CN201910212822 A CN 201910212822A CN 109799302 A CN109799302 A CN 109799302A
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Abstract
The invention discloses the nearly online test methods of medium volatile organic compound, comprising: a sampling pipe, to acquire target substance；Adsorption/desorption system, including air-flow switching valve and cold-trap pipe, the cold-trap pipe is interior to load adsorbent；The outlet end of the air-flow switching valve of the adsorption/desorption system is connect by a sample transfer line with GC/MS Analysis system；The method specifically includes: step S1, and sampling pipe acquires standard sample or surrounding air, and the temperature collection of sampling pipe is between 220~290 DEG C；Step S2, described two cold-trap pipes in turn adsorb the target substance, and each cold-trap pipe adsorbs 120~240min in turn；Target substance is desorbed at 300~350 DEG C using inert gas in step S3, the cold-trap pipe；Step S4, GC/MS Analysis system are tested and analyzed.Test is continuously tracked using what the technical program was able to achieve IVOCs mean concentration.
Description
Technical field
The invention belongs to chemically or physically analysis technical field more particularly to medium volatile organic compounds closely to examine online
Survey method.
Background technique
Since saturated concentration (C*) in an atmosphere is different, organic compound can be divided into following several classes: half volatile has
Machine compound (semi-volatility organic compounds, SVOCs), saturated concentration range are 10-2μg/m3<
C* < 103μg/m3；Medium volatile organic compound (intermediate volatile organic compounds,
IVOCs), saturated concentration range is 103μg/m3< C* < 106μg/m3；Volatile organic compounds (Volatile
Organic Compounds, VOCs), saturated concentration range is C* > 106μg/m3。
VOCs saturated concentration range corresponds to C3~C10N-alkane between, IVOCs saturated concentration range correspond to C12
~C22N-alkane between.Laboratory research shows PM in IVOCs and atmosphere2.5In secondary organic aerosol
(secondary organic aerosols, SOA) component is closely related, and IVOCs can efficiently be converted into SOA.But current state
The interior measurement to organic constituents and content is primarily directed to VOCs, because the boiling point of VOCs is lower, generally at 50~250 DEG C,
Saturated vapour pressure is at room temperature more than 133.32Pa.IVOCs is relatively low relative to the concentration level of VOCs in the environment, viscosity phase
To larger, moreover, IVOCs saturated concentration is 103~106μg/m3Between standard organic matter be essentially liquid, it is difficult to use
The mode of calibration VOCs carries out IVOCs calibration.Thermal desorption instrument joint gas-chromatography/matter is based primarily upon to the analysis of IVOCs at present
Spectrum carries out collected offline and analysis, has lower temporal resolution, lacks the dirt that observation IVOCs is continuously tracked in effective means
Dye is horizontal, and the contamination characteristics that IVOCs cannot be continuously tracked change with time trend, can not obtain accurately different IVOCs
Monomer and the exact response relation of SOA, it is difficult to the contribution that Scientific evaluation IVOCs generates SOA.
Summary of the invention
The present invention is directed to the technical issues of level of pollution for being difficult to be continuously tracked test IVOCs in the prior art, and purpose exists
In the nearly online test method of offer medium volatile organic compound.
The present invention provides a kind of medium volatile organic compound nearly online test method, comprising: one can independent temperature control
Sampling pipe, to acquire standard sample or surrounding air；Adsorption/desorption system, including the first, second air-flow switching valve and at least
The outlet end of two cold-trap pipes that can be adsorbed in turn with desorption, the first end of the cold-trap pipe and sampling pipe respectively with the first air-flow
Three arrival ends of switching valve connect, and the adsorption/desorption system is equipped at the outlet end downstream of the first air-flow switching valve
The second end of bypass line, the cold-trap pipe is connected to by the second air-flow switching valve with extraneous and inert gas pipeline, described cold
Trap pipe successively loads the adsorbent to grow from weak to strong from first end to second end；First air-flow switching valve of the adsorption/desorption system
Outlet end, connect by a sample transfer line with the chromatographic column arrival end of GC/MS Analysis system；The method
Specifically include: step S1, sampling pipe acquire standard sample or surrounding air, the temperature collection of sampling pipe be 220~290 DEG C it
Between；Step S2, collected standard sample or surrounding air enter the adsorption/desorption system, and described two cold-trap pipes are right in turn
The target substance is adsorbed, and each cold-trap pipe adsorbs 120~240min in turn, during cold-trap pipe adsorbs the target substance
Temperature be 5~20 DEG C；Step S3, the cold-trap pipe after adsorbed target substance are taken off at 300~350 DEG C using inert gas
Attached target substance；Step S4, the target substance after desorption are loaded into GC/MS Analysis system by inert gas and are detected
Analysis.
It is preferred that the sampling pipe front end connects filter holder, quartz fibre filter membrane is equipped in the filter holder.
It is preferred that the sampling pipe front end is separately connected standard sample injection end and inert gas input terminal, the mark
Quasi- sample injection end is equipped with gas-chromatography dottle pin, and standard sample is injected into institute by the gas-chromatography dottle pin by injection needle
State sampling pipe；The inert gas input terminal is equipped with pressure maintaining valve, is swept into the adsorption/desorption system for inert blowing gas and provides
Stable and acceptable stream pressure.
It is preferred that the sampling pipe connects an independent temperature control system by external cable.
It is preferred that the adsorbent is bead, ketjenblack EC C and/or ketjenblack EC B；The cold-trap pipe from
First end is successively filled with to second end: bead and ketjenblack EC C, or is successively filled with: bead, ketjenblack EC
C and ketjenblack EC B；Load the absorption of glass fibre and/or metal mesh to fixed cold-trap pipe both ends in cold-trap pipe both ends
Glass fibre and/or metal mesh are loaded between agent and adsorbent to separate different adsorbents.
It is preferred that the sampling flow velocity of the sampling pipe is 50~120mL/min, the shunting speed of the cold-trap pipe is 10
~30mL/min, the column flow rate of the GC/MS Analysis system are 1~1.5mL/min.
It is preferred that the temperature during cold-trap pipe adsorbs the target substance is 5~20 DEG C.
It is preferred that the column model of the GC/MS Analysis system is DB-5MS.
It is preferred that the inert gas is high-purity helium in step S3, the cold-trap pipe after adsorbed target substance exists
High-purity helium, which is flowed down, to be risen to after 300~350 DEG C with the speed of 32~40 DEG C/s and keeps the temperature 5~15min.
The positive effect of the present invention is that:
(1) in the prior art, IVOCs is relatively low relative to the concentration level of VOCs in the environment, and viscosity is relatively large,
IVOCs saturated concentration is 103~106μg/m3Between standard organic matter be essentially liquid, it is difficult to using calibration and continuous to receive
The mode of set analysis VOCs carries out IVOCs calibration；The present invention is by improvement part key parameter and accessory, such as adsorption/desorption system
Adsorption time, sampling pipe temperature, cold-trap pipe, adsorbent, desorption parameter etc., realize and carried out in a manner of using VOCs is demarcated
IVOCs calibration, so that realizing IVOCs concentration is continuously tracked test.
(2) on the basis of the present invention detects VOCs in the prior art, Partial key parameter and accessory are only improved, is just realized
IVOCs mean concentration is continuously tracked, and structure is simple, low in cost.
(3) present invention is applied to the continuous online observation analysis of gaseous state IVOCs in actual environment air the result shows that continuous prison
IVOCs has similar distribution characteristics, i.e. C in the actual air measured12~C17And the polycyclic aromatic hydrocarbon of low ring is with higher
Concentrations and recall rate, concentration difference is between 3~14% between multiple repairing weld result monomer.The result shows that the present invention exists
Reliability with higher in the detection of actual sample.
(4) in the prior art, when carrying out nearly on-line analysis to VOCs in ambient air, allow the absorption of adsorption/desorption system
Time is 99min, and the temperature of sampling pipe, air-flow switching valve and sample transfer pipeline allows to set by an input window control
Determining maximum temperature is 210 DEG C, and the selection of maximum temperature value is the maximum receiving energy of material (polytetrafluoroethylene (PTFE)) by air-flow switching valve
Power is limited.Compared with prior art, the present invention in sets itself adsorption/desorption system adsorption time and adsorption temp, absorption temperature
Degree is 5~20 DEG C, and desorption temperature is 300~350 DEG C, the other independent temperature control of sampling pipe, the sample temperature of sampling pipe is 220~
Between 290 DEG C, the nearly on-line checking of IVOCs is helped to realize.
It is described further below with reference to technical effect of the attached drawing to design of the invention, specific structure and generation, with
It is fully understood from the purpose of the present invention, feature and effect.
Detailed description of the invention
Fig. 1 is that medium volatile organic compound is close in the nearly online test method of medium volatile organic compound of the present invention
The structural schematic diagram of on-line measuring device；
Fig. 2 is the flow diagram of the nearly online test method of medium volatile organic compound of the present invention；
Fig. 3 is cold-trap pipe operation schematic diagram in the nearly online test method of medium volatile organic compound of the present invention；
Fig. 4 is that cold-trap pipe A adsorption gas flow trend is shown in the nearly online test method of medium volatile organic compound of the present invention
It is intended to；
Fig. 5 is that cold-trap pipe B desorption air-flow trend is shown in the nearly online test method of medium volatile organic compound of the present invention
It is intended to；
Fig. 6 is Performance evaluation criterion sample feeding end in the nearly online test method of medium volatile organic compound of the present invention
Schematic diagram；
Fig. 7 is sampling environment air sample introduction end signal in the nearly online test method of medium volatile organic compound of the present invention
Figure.
Specific embodiment
Drawing reference numeral explanation: sampling pipe 10, quartz fibre filter membrane 11, filter holder 12, pressure maintaining valve 13, gas-chromatography dottle pin
14, injection needle 15, cold-trap pipe A21, cold-trap pipe B22, the first air-flow switching valve 23, chromatograph box 30, sample transfer pipeline 40,
Method and step S1~S4.
As shown in Fig. 1~5, a kind of nearly on-line measuring device of medium volatile organic compound is successively wrapped along air flow direction
Include sampling pipe 10, adsorption/desorption system and GC/MS Analysis system.The sampling pipe 10 can independent temperature control, specifically,
Sampling pipe 10 is connected in external independent temperature system by an external cable, the independent temperature system of the outside
Temperature accuracy is ± 1 DEG C.Wrap up one layer of heat preservation material in 10 surface of sampling pipe.Sampling pipe 10 set range as room temperature~
300 DEG C, 10 temperature collection setting range of sampling pipe is between 220~290 DEG C.Preferably, as shown in fig. 6,10 right end of sampling pipe
Filter holder 12 is connected, quartz fibre filter membrane 11 is installed in the filter holder 12, to acquire gaseous state IVOCs in surrounding air
(hereinafter referred to as target substance).Specifically, surrounding air enters quartz fibre filter membrane 11, quartz fibre filter membrane 11 in the direction of the arrow
Granulating material is intercepted, by the processing of quartz fibre filter membrane 11, the surrounding air containing gaseous target materials enters sampling
In pipe 10, the quartz fibre filter membrane 11 of replacement in every 48 hours.Preferably, as shown in fig. 7,10 front end of the sampling pipe connects respectively
Standard sample injection end and inert gas input terminal are connect, the standard sample injection end is equipped with gas-chromatography dottle pin 14, injection
Standard sample is injected into the sampling pipe 10 by the gas-chromatography dottle pin 14 by syringe needle 15；On the inert gas input terminal
Equipped with pressure maintaining valve 13, the adsorption/desorption system is swept into for inert blowing gas, stable and acceptable stream pressure is provided.
As shown in Fig. 1~5, the adsorption/desorption system includes cold-trap pipe A21 and cold-trap pipe B22, cold-trap pipe A21 and cold-trap
The upper end of pipe B22 and the outlet end of sampling pipe 10 are connect with three arrival ends of the first air-flow switching valve 23 respectively, cold-trap pipe A21
(do not shown in figure with the lower end of cold-trap pipe B22 by the second air-flow switching valve (not shown) and extraneous and inert gas pipeline
It is connected to out).Cold-trap pipe A21 and cold-trap pipe B22 from sampling air flow enter opening's edge sampling air flow trend, successively load adsorption capacity by
Weak to arrive strong adsorbent, the adsorption/desorption system is equipped with isocon at the outlet end downstream of the first air-flow switching valve 23
Line (as shown by the arrows in Figure 1).Preferably, the adsorbent includes bead, ketjenblack EC B (i.e. Carbopack B), stone
Inkization carbon black C (i.e. Carbopack C)；The cold-trap pipe is successively filled with from first end to second end: bead and graphitization
Carbon black C, or be successively filled with: bead, ketjenblack EC C and ketjenblack EC B；Cold-trap pipe A21 and the both ends cold-trap pipe B22
And glass fibre and/or metal mesh are loaded between adsorbent.Specifically, cold-trap pipe is glass material, model T-12M is long
14cm, internal diameter 3mm, outer diameter 4mm, bead are pickling, and 212-300 μm, ketjenblack EC B and ketjenblack EC C are 60/80
Mesh, as shown in A~B in Fig. 3, there are two types of the methods of filling adsorbent by cold-trap pipe A21 and cold-trap pipe B22, specifically, the first
Adsorbent packing method successively loads glass fibre, bead (long 10mm), glass fibre, graphitization as shown in A in Fig. 3
Carbon black C (long 15mm), glass fibre (glass fibre can be replaced with metal mesh)；In second of adsorbent packing method such as Fig. 3 in B
It is shown, successively load glass fibre, bead (long 10mm), glass fibre, ketjenblack EC C (long 12mm), glass fibre, stone
Inkization carbon black B (long 3mm), glass fibre (glass fibre can be replaced with metal mesh).Wherein, cold-trap pipe A21, cold-trap pipe B22 two
The glass fibre or metal mesh at end play fixed function, and the glass fibre or metal mesh between adsorbent play buffer action.
Cold-trap pipe A21 and cold-trap pipe B22 wheel is realized by the first air-flow switching valve 23 between cold-trap pipe A21, cold-trap pipe B22
Stream adsorbs the target substance, and each cold-trap pipe adsorbs 120~240min of air in turn.Cold-trap pipe A21 adsorption gas flow
Trend, cold-trap pipe B22 desorption air-flow trend are as shown in Figures 4 and 5.Specifically, target substance is adsorbed during collecting air
In adsorbent in cold-trap, other air then pass through cold-trap pipe and are discharged into ambient air.At the end of cold-trap pipe B22 absorption, this
When cold-trap pipe A21 absorption start, meanwhile, cold-trap pipe B22 absorption target substance carried out at 300~350 DEG C by inert gas
Target substance a part of desorption, desorption passes through (210 DEG C) the loading gas chromatography/mass spectrometries of sample transfer pipeline 40 by inert gas
Chromatographic column front end in the chromatograph box 30 of analysis system, another portion are discharged into surrounding air via bypass line；As cold-trap pipe A21
When absorption is completed, the target substance of cold-trap pipe A21 absorption is desorbed at 300~350 DEG C by inert gas, the target of desorption
Chromatograph box 30 of the substance by inert gas by (210 DEG C) of sample transfer pipeline 40 loading GC/MS Analysis systems
Interior chromatographic column front end, another portion are discharged into surrounding air via bypass line, and cold-trap pipe B22 starts to sample again at this time, so follow
Ring is reciprocal.Cold-trap pipe A21 and cold-trap pipe B22, which takes turns to operate, to be realized to the continuous absorptive collection of surrounding air.It should be noted that
Calibration to IVOCs, generally with gaseous state standard specimen by Soviet Union's Ma tank sampling enter cold-trap pipe, be then desorbed, then by gas-chromatography/
Mass spectrometry system is analyzed.Preferably, cold-trap pipe A21 and cold-trap pipe B22 sampling period temperature setting are 5~10 DEG C.Institute
The column model for stating GC/MS Analysis system is DB-5MS.
As shown in Fig. 1~2, a kind of nearly online test method of medium volatile organic compound is specifically included: step S1,
Sampling pipe acquires standard sample or surrounding air, and the temperature collection of sampling pipe is between 220~290 DEG C；Step S2, it is collected
Standard sample or surrounding air enter the adsorption/desorption system, and described two cold-trap pipes in turn inhale the target substance
It is attached, each cold-trap pipe 120~240min of adsorbed target substance in turn；Step S3, the cold-trap pipe after adsorbed target substance are adopted
Target substance is desorbed at 300~350 DEG C with inert gas；Step S4, the target substance after desorption are loaded into gas by inert gas
Phase Gas Chromatography/Mass Spectrometry Analysis system is tested and analyzed.Preferably, the sampling flow velocity of the sampling pipe 10 is 50~120mL/min,
The shunting speed of the cold-trap pipe is 10~30mL/min, the column flow rate of the GC/MS Analysis system is 1~
1.5mL/min.The adsorption time of the adsorption/desorption system is between 120~240min.In step S3, the inert gas is
High-purity helium, the cold-trap pipe after collecting target substance are risen to after 350 DEG C simultaneously under high-purity helium stream with the speed of 40 DEG C/s
Keep the temperature 10min.After 30 temperature program of chromatograph box of the GC/MS Analysis system is 60 DEG C of 8~10min of stop,
300 DEG C are warming up to 18 DEG C/min, stops 20min.The mass spectral analysis operating condition of the GC/MS Analysis system is
The source EI voltage 70eV, filament voltage 1.80eV, filament delay time 10min, using full scan operating mode, scanning of the mass spectrum range
For 45-500m/z, the gas chromatographic column connection ion source transmission line temperature in chromatograph box 30 is 300 DEG C.
Embodiment 1
Because medium volatile organic compound saturated concentration range corresponds to C12~C22N-alkane between, therefore make
N-alkane is used to carry out the foundation of method, performance evaluation and practical application as the representative of medium volatile organic compound.Newly
The method of foundation is suitable for all volatility ranges in C12~C22Medium volatile organic matter.
The present embodiment is with C12~C22N-alkane is representativeness object, the method performance of assay IVOCs and is adopted
Sample analyzes practical application two parts.
Henchnmrk test method is similar with the actual samples of embodiment 2, the difference is that henchnmrk test method is collected
Not instead of surrounding air, replace actual environment air with high-purity helium.Sampling pipe temperature is set as 250 DEG C, such as Fig. 6 institute
Show, by the C containing certain mass12~C22Linear paraffin standard sample is injected by injection needle 15 by gas-chromatography dottle pin 14
After sampling pipe 10, then sampling pipe 10 and high-purity helium piping connection, high-purity helium exist along pressure maintaining valve 13 is entered shown in arrow
Sampling pipe 10, purge time 180min are purged with high-purity helium under 100mL/min.Liquid standard sample is waved after helium purge
It sends out and collects to cold-trap pipe adsorbent.The standard target object of preanalysis is loaded into cold-trap pipe A21 or cold-trap pipe B22, mesh by helium
Mark substance is adsorbed on the adsorbent in cold-trap pipe, and helium is then discharged into surrounding air.After the completion of purging, desorption work thereafter
And gas-chromatography and mass spectral analysis conditional parameter it is identical as the analysis parameter of the actual samples of embodiment 2.
The evaluation parameter of henchnmrk test method includes object recovery efficiency, standard curve regression coefficient, analysis knot
The reproducibility of fruit, the detection limit of instrument and sampling penetration volume, the results are shown in Table 1 for design parameter, and table 1, which is that the present invention is medium, to be waved
IVOCs n-alkane retention time and qualitative, quantitative scan ion in the hair property nearly online test method of organic compound:
1 IVOCs n-alkane retention time of table and qualitative, quantitative scan ion
(1) recovery efficiency: continuous operation cold-trap pipe twice, does not have the target of discovery remnants in second of desorption process
Object.Therefore, the definition of recovery efficiency is that the amount for the object that the first operating analysis obtains accounts for the target object amount for running measure twice
The percentage of summation.Since not detecting object in second of desorption process, illustrate that first time desorption process will solution
The object of analysis is fully incorporated analysis system.The object rate of recovery analyzed is 100%；
(2) standard curve: the standard curve established based on external standard method, by 5 different mass gradients (0.3,1.0,3.0,
10,30ng) C12~C22The power exponential function relationship of n-alkane is drawn, linear regression coeffficient, R20.9200-0.9972 it
Between；
(3) reproducibility: the C by being respectively filled in 3ng and 10ng in cold-trap pipe12~C22N-alkane, result after analyzing 5 times
Relative standard deviation (RSD, n=5) evaluation, mark-on sample be 3ng when, RSD within 20%, standard specimen be 10ng when, remove C22
Outside N-alkanes, the RSD of other objects is within 17%；
(4) instrument detection limit: detection limit is defined as concentration when signal-to-noise ratio is 3/1.It is sensitive for three times noise and instrument
Ratio, detection are limited to < 0.074 μ g/m3；
(5) breakthrough experiment: two cold-trap pipes of series connection, mark-on 3.0ng n-alkane in cold-trap pipe, 100mL/min nitrogen according to
It is secondary to pass through two cold-trap pipes (for 3 hours), analyze target compound in second cold-trap pipe, with second cold-trap pipe whether
There is object detection measurement system with the presence or absence of penetrating, as shown in table 2, table 2 is that medium volatile organic compound of the present invention is close
Breakthrough experiment result in online test method.For the safe sampling volume for ensuring 1.8L, when loading bead is 10mm, graphite
Change the length need > 15mm of carbon black C, or the ketjenblack EC B in filled column addition 3mm long.
2 breakthrough experiment of table
Embodiment 2
Sample collection is surrounding air, and sampling specific steps include:
As shown in fig. 7, firstly, setting 10 temperature collection of sampling pipe as 250 DEG C, sampling flow velocity is 100mL/min, sampling pipe
The granulating material that the quartz fibre filter membrane 11 of 10 front ends intercepts in surrounding air contains by the processing of quartz fibre filter membrane 11
There is the surrounding air of gaseous state IVOCs to enter in sampling pipe 10；Secondly, collected surrounding air enters the adsorption/desorption system
Cold-trap pipe A21, the cold-trap pipe B22 of system, the sampling time of adsorption/desorption system are 180min.Two cold-trap pipes are in turn to the environment
Target substance in air is adsorbed and is desorbed work.
Target substance a part after desorption is delivered to chromatography via sample transfer pipeline 40 (210 DEG C) together with high-purity helium
Gas chromatographic column front end in post case 30, hence into GC/MS Analysis system, another part is arranged via bypass line
Enter surrounding air, cold-trap pipe shunts speed: 18.8mL/min.
Finally, GC/MS Analysis system is tested and analyzed.Wherein, GC/MS Analysis system carries out
When gas chromatographic analysis, chromatographic column uses constant current mode, column flow rate 1.2mL/min.30 temperature program of chromatograph box is
After initial temperature is 60 DEG C of stop 10min, 300 DEG C are warming up to 18 DEG C/min speed, then in 300 DEG C of stop 20min.Gas
Phase Gas Chromatography/Mass Spectrometry Analysis system carries out mass spectrum and chromatography.Wherein, when analysis system is analyzed by mass spectrometry, ion source is in electricity
Work (EI, 70eV) under sub- impact mode.Ion source and the temperature of transmission line are 300 DEG C.Sample is with full scan mode monitoring.
C in the online tracking observation ambient air of 3 IVOCs of table12~C22The concentration level of n-alkane
As shown in table 3, table 3 be the nearly online test method of medium volatile organic compound of the present invention in IVOCs online with
C in track observing environment atmosphere12~C22The concentration level of n-alkane, the present invention are applied to gaseous state in actual environment air
The continuous three days online observations of IVOCs (continue sampling operation mode).Wherein continuous sample is carried out on September 28th~30,2018
Product acquisition and analysis.Analysis has similar distribution characteristics, i.e. C the result shows that continuously monitoring IVOCs in obtained actual air12
~C17And the polycyclic aromatic hydrocarbon concentrations with higher and recall rate of low ring, the furthermore double sampling of September 29 days on the same day
As a result concentration differs between 3~14% between monomer.The result shows that the present invention is with higher in the detection of actual sample
Reliability.
In conclusion it is flat to be able to achieve IVOCs the invention discloses the nearly online test method of medium volatile organic compound
Test is continuously tracked in equal concentration.
Claims (9)
1. a kind of nearly online test method of medium volatile organic compound characterized by comprising
One can independent temperature control sampling pipe, to acquire standard sample or surrounding air；
Adsorption/desorption system can adsorb the cold-trap pipe with desorption, institute including the first, second air-flow switching valve and at least two in turn
The outlet end of the first end and sampling pipe of stating cold-trap pipe is connect with three arrival ends of the first air-flow switching valve respectively, the absorption
Desorption system is equipped with bypass line at the outlet end downstream of the first air-flow switching valve, and the second end of the cold-trap pipe passes through
Second air-flow switching valve is connected to extraneous and inert gas pipeline, and the cold-trap pipe is successively loaded from first end to second end by weak
To strong adsorbent；
The outlet end of first air-flow switching valve of the adsorption/desorption system, passes through a sample transfer line and gas-chromatography/matter
The chromatographic column arrival end of spectrum analysis system connects；
The method specifically includes:
Step S1, sampling pipe acquire standard sample or surrounding air, and the temperature collection of sampling pipe is between 220~290 DEG C；
Step S2, collected standard sample or surrounding air enter the adsorption/desorption system, and described two cold-trap pipes are in turn
The target substance is adsorbed, each cold-trap pipe adsorbs 120~240min in turn, and cold-trap pipe adsorbs the target substance phase
Between temperature be 5~20 DEG C；
Target substance is desorbed at 300~350 DEG C using inert gas in step S3, the cold-trap pipe after adsorbed target substance；
Step S4, the target substance after desorption are loaded into GC/MS Analysis system by inert gas and are tested and analyzed.
2. the nearly online test method of medium volatile organic compound as described in claim 1, it is characterised in that: the sampling
Pipe front end connects filter holder, is equipped with quartz fibre filter membrane in the filter holder.
3. the nearly online test method of medium volatile organic compound as described in claim 1, it is characterised in that: the sampling
Pipe front end is separately connected standard sample injection end and inert gas input terminal, and the standard sample injection end is equipped with gas-chromatography
Standard sample is injected into the sampling pipe by the gas-chromatography dottle pin by dottle pin, injection needle；The inert gas input
End is equipped with pressure maintaining valve, is swept into the adsorption/desorption system for inert blowing gas and provides stable and acceptable stream pressure.
4. the nearly online test method of medium volatile organic compound as described in claim 1, it is characterised in that: the sampling
Pipe connects an independent temperature control system by external cable.
5. the nearly online test method of medium volatile organic compound as described in claim 1, it is characterised in that: the absorption
Agent is bead, ketjenblack EC C and/or ketjenblack EC B；The cold-trap pipe is successively filled with from first end to second end:
Bead and ketjenblack EC C, or be successively filled with: bead, ketjenblack EC C and ketjenblack EC B；The cold-trap pipe
Both ends filling glass fibre and/or metal mesh load glass between the adsorbent and adsorbent to fixed cold-trap pipe both ends
Fiber and/or metal mesh are to separate different adsorbents.
6. the nearly online test method of medium volatile organic compound as described in claim 1, it is characterised in that: the sampling
The sampling flow velocity of pipe is 50~120mL/min, and the shunting speed of the cold-trap pipe is 10~30mL/min, the gas-chromatography/
The column flow rate of mass spectrometry system is 1~1.5mL/min.
7. the nearly online test method of medium volatile organic compound as described in claim 1, it is characterised in that: cold-trap pipe is inhaled
Temperature during the attached target substance is 5~20 DEG C.
8. the nearly online test method of nonpolarity medium volatile organic compound as described in claim 1, it is characterised in that: institute
The column model for stating GC/MS Analysis system is DB-5MS.
9. the nearly online test method of medium volatile organic compound as claimed in claim 7, it is characterised in that: step S3
In, the inert gas is high-purity helium, the cold-trap pipe after adsorbed target substance under high-purity helium stream with 32~40 DEG C/
The speed of s rises to after 300~350 DEG C and keeps the temperature 5~15min.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| CN111579315A (en) * | 2020-05-28 | 2020-08-25 | 上海市环境科学研究院 | VOCs and IVOCs simultaneous on-line collecting and detecting method |
| CN111579315B (en) * | 2020-05-28 | 2023-06-02 | 上海市环境科学研究院 | VOCs and IVOCs simultaneous online collection and detection method |
| CN112924576A (en) * | 2021-01-25 | 2021-06-08 | 江苏东科分析仪器有限公司 | Environment malodorous gas online monitoring system and method thereof |
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